Safety of rapid intravenous valproate infusion in pediatric patients

Optimizing Status Epilepticus Management in the Emergency Department: It's About Time

Status epilepticus (SE) is a frequent medical emergency that requires expedited treatment to avoid the ensuing high incidence of morbidity and mortality associated with prolonged seizures. Protracted seizure duration itself has the potential to result in maladaptive neuronal responses that can not only further increase seizure duration and worsen clinical outcomes but also lead to reduced responsiveness to pharmacotherapy. Benzodiazepines are consistently recommended as first-line treatment due to their rapid onset and efficacy in terminating seizures, followed by the emergent administration of an antiepileptic drug (AED). Various benzodiazepine and AED options are recommended and can be utilized in this setting, all with their own unique advantages and challenges. With time at a premium, agents should be selected that can be rapidly administered and have an advantageous pharmacokinetic profile in order to limit seizure duration and optimize outcomes. The intent of this review is to provide an outline of the importance of time-to-treatment implementation in this setting, assess the landscape of options that may provide timing advantages, and examine potential strategies for deploying expeditious therapy.

Drug management for acute tonic-clonic convulsions including convulsive status epilepticus in children

BACKGROUND

Tonic-clonic convulsions and convulsive status epilepticus (currently defined as a tonic-clonic convulsion lasting at least 30 minutes) are medical emergencies and require urgent and appropriate anticonvulsant treatment. International consensus is that an anticonvulsant drug should be administered for any tonic-clonic convulsion that has been continuing for at least five minutes. Benzodiazepines (diazepam, lorazepam, midazolam) are traditionally regarded as first-line drugs and phenobarbital, phenytoin and paraldehyde as second-line drugs. This is an update of a Cochrane Review first published in 2002 and updated in 2008.

OBJECTIVES

To evaluate the effectiveness and safety of anticonvulsant drugs used to treat any acute tonic-clonic convulsion of any duration, including established convulsive (tonic-clonic) status epilepticus in children who present to a hospital or emergency medical department.

SEARCH METHODS

For the latest update we searched the Cochrane Epilepsy Group's Specialised Register (23 May 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 23 May 2017), MEDLINE (Ovid, 1946 to 23 May 2017), ClinicalTrials.gov (23 May 2017), and the WHO International Clinical Trials Registry Platform (ICTRP, 23 May 2017).

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing any anticonvulsant drugs used for the treatment of an acute tonic-clonic convulsion including convulsive status epilepticus in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and extracted data. We contacted study authors for additional information.

MAIN RESULTS

The review includes 18 randomised trials involving 2199 participants, and a range of drug treatment options, doses and routes of administration (rectal, buccal, nasal, intramuscular and intravenous). The studies vary by design, setting and population, both in terms of their ages and also in their clinical situation. We have made many comparisons of drugs and of routes of administration of drugs in this review; our key findings are as follows:(1) This review provides only low- to very low-quality evidence comparing buccal midazolam with rectal diazepam for the treatment of acute tonic-clonic convulsions (risk ratio (RR) for seizure cessation 1.25, 95% confidence interval (CI) 1.13 to 1.38; 4 trials; 690 children). However, there is uncertainty about the effect and therefore insufficient evidence to support its use. There were no included studies which compare intranasal and buccal midazolam.(2) Buccal and intranasal anticonvulsants were shown to lead to similar rates of seizure cessation as intravenous anticonvulsants, e.g. intranasal lorazepam appears to be as effective as intravenous lorazepam (RR 0.96, 95% CI 0.82 to 1.13; 1 trial; 141 children; high-quality evidence) and intranasal midazolam was equivalent to intravenous diazepam (RR 0.98, 95% CI 0.91 to 1.06; 2 trials; 122 children; moderate-quality evidence).(3) Intramuscular midazolam also showed a similar rate of seizure cessation to intravenous diazepam (RR 0.97, 95% CI 0.87 to 1.09; 2 trials; 105 children; low-quality evidence).(4) For intravenous routes of administration, lorazepam appears to be as effective as diazepam in stopping acute tonic clonic convulsions: RR 1.04, 95% CI 0.94 to 1.16; 3 trials; 414 children; low-quality evidence. Furthermore, we found no statistically significant or clinically important differences between intravenous midazolam and diazepam (RR for seizure cessation 1.08, 95% CI 0.97 to 1.21; 1 trial; 80 children; moderate-quality evidence) or intravenous midazolam and lorazepam (RR for seizure cessation 0.98, 95% CI 0.91 to 1.04; 1 trial; 80 children; moderate-quality evidence). In general, intravenously-administered anticonvulsants led to more rapid seizure cessation but this was usually compromised by the time taken to establish intravenous access.(5) There is limited evidence from a single trial to suggest that intranasal lorazepam may be more effective than intramuscular paraldehyde in stopping acute tonic-clonic convulsions (RR 1.22, 95% CI 0.99 to 1.52; 160 children; moderate-quality evidence).(6) Adverse side effects were observed and reported very infrequently in the included studies. Respiratory depression was the most common and most clinically relevant side effect and, where reported, the frequency of this adverse event was observed in 0% to up to 18% of children. None of the studies individually demonstrated any difference in the rates of respiratory depression between the different anticonvulsants or their different routes of administration; but when pooled, three studies (439 children) provided moderate-quality evidence that lorazepam was significantly associated with fewer occurrences of respiratory depression than diazepam (RR 0.72, 95% CI 0.55 to 0.93).Much of the evidence provided in this review is of mostly moderate to high quality. However, the quality of the evidence provided for some important outcomes is low to very low, particularly for comparisons of non-intravenous routes of drug administration. Low- to very low-quality evidence was provided where limited data and imprecise results were available for analysis, methodological inadequacies were present in some studies which may have introduced bias into the results, study settings were not applicable to wider clinical practice, and where inconsistency was present in some pooled analyses.

AUTHORS' CONCLUSIONS

We have not identified any new high-quality evidence on the efficacy or safety of an anticonvulsant in stopping an acute tonic-clonic convulsion that would inform clinical practice. There appears to be a very low risk of adverse events, specifically respiratory depression. Intravenous lorazepam and diazepam appear to be associated with similar rates of seizure cessation and respiratory depression. Although intravenous lorazepam and intravenous diazepam lead to more rapid seizure cessation, the time taken to obtain intravenous access may undermine this effect. In the absence of intravenous access, buccal midazolam or rectal diazepam are therefore acceptable first-line anticonvulsants for the treatment of an acute tonic-clonic convulsion that has lasted at least five minutes. There is no evidence provided by this review to support the use of intranasal midazolam or lorazepam as alternatives to buccal midazolam or rectal diazepam.

Efficacy and safety of intravenous valproate for status epilepticus: a systematic review

INTRODUCTION

The effectiveness of valproate (VPA) in the treatment of focal and generalized epilepsies is well established. The drug has a wide spectrum of action, good tolerability, and has been available as an injectable formulation since 1993. Despite the lack of class A evidence, it has been used extensively in various forms of status epilepticus (SE).

AIM

Our aim was to present a systematic review of data from randomized and non-randomized controlled trials to evaluate the efficacy and safety of intravenous VPA for the treatment of SE.

METHODS

Data sources included MEDLINE, back tracing of references in pertinent studies, and contact with the manufacturer of VPA (Sanofi-Aventis).

RESULTS

Overall, the search strategy yielded 433 results (425 MEDLINE, seven congress abstracts, one unpublished study); after excluding duplicate publications and case reports, 30 studies were identified (the earliest was published in 1993, the most recent in 2012); ten were controlled (six randomized controlled trials, four non-randomized controlled studies), and 20 uncontrolled trials (eight prospective observational studies, 12 retrospective case series). The cumulative literature describes the experiences of 860 patients with various forms of SE treated with intravenous VPA. The overall response rate to abrogate SE was 70.9% (601/848; 95% confidence interval [CI] 67.8-73.9). Response rates to intravenous VPA were better in children than in adults and did not differ between the SE types. The most commonly reported effective doses were between 15 and 45 mg/kg in bolus (6 mg/kg/min) followed by 1-3 mg/kg/h infusion. Safety studies of intravenous VPA administration in patients with SE showed a low incidence of adverse events overall (<10%), mainly dizziness, thrombocytopenia, and mild hypotension, which was independent of infusion rates. Of note, good cardiovascular and respiratory tolerability was observed in these studies, even at high doses and fast infusion rates (up to 30 mg/kg at 10 mg/kg/min), despite multiple morbidities or other antiepileptic drugs. The most serious concern relates to the possibility of acute encephalopathy, sometimes related to hepatic abnormalities or hyperammonemia.

CONCLUSIONS

The published experience is consistent with VPA being a safe and effective therapeutic option for patients with established SE who have previously failed conventional first-line treatment with benzodiazepines, but high-quality randomized controlled trials are needed to inform clinicians on its comparative effectiveness in SE.

Efficacy and safety of intravenous sodium valproate versus phenobarbital in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children: a randomised trial

Status epilepticus and acute prolonged seizures are the most commonly occurring neurological emergencies in children. Such events have high morbidity and mortality rates along with poor long-term outcomes, depending on their duration and causes. Therefore, such seizures warrant urgent treatment using appropriate doses of anticonvulsants. Benzodiazepines, phenobarbital, and phenytoin are the most commonly used anticonvulsants for controlling status epilepticus and acute prolonged seizures. However, these medications have several well-known adverse effects. Previous studies on both adults and children have shown the efficacy and safety of rapid infusion of valproate in controlling status epilepticus. However, few well-designed randomised trials have been carried out in children, and there remains a paucity of data regarding intravenous sodium valproate use in children. Therefore, our aim was to compare the efficacy and safety of rapid loading of valproate with those of intravenous phenobarbital in children with status epilepticus and acute prolonged seizures. Sixty children (30 in each group) with convulsive status epilepticus and acute prolonged seizures were enrolled and randomly assigned to receive either valproate or phenobarbital. The main outcome variable was termination of all convulsive activity within 20 min of starting anticonvulsant infusion. Intravenous rapid loading of valproate was successful in seizure termination in (27/30, 90%) of patients compared to phenobarbital (23/30, 77%) (p = 0.189). Clinically significant adverse effects occurred in 74% patients of the phenobarbital group and 24% patients of the valproate group (p < 0.001). In conclusion, rapid loading of valproate is effective and safe in controlling convulsive status epilepticus and acute prolonged convulsive seizures in children. Intravenous valproate should be considered as a suitable choice for terminating status epilepticus and acute prolonged seizures in children.

Update on the newer antiepileptic drugs in child neurology: advances in treatment of pediatric epilepsy

The goal of epilepsy treatment is the prevention of recurrent seizures, and antiepileptic drugs (AEDs) are the mainstay. Uncontrolled seizures may cause medical, developmental, and psychologic disturbances. Treatment advances include 1) identification of the basic mechanisms of epilepsy and action of AEDs, 2) the introduction of many new AEDs, and 3) the use of neurostimulation, starting with vagus nerve stimulation. We must balance the efficacy of an AED versus its side effects, which if persistent, lead to patient discontinuation of the AED. Although all AEDs have a proven efficacy, they are differentiated by their efficacy for a given seizure type or epilepsy syndrome versus the side effects or tolerability. The many new AEDs give us a larger armamentarium for epilepsy treatment. We refer to studies and expert opinion consensus.

Pharmacokinetics and clinical application of intravenous valproate in Thai epileptic children

Roles of intravenous administration of valproate in status epilepticus and serial seizures are documented in adults and children. Pharmacokinetic parameters are necessary to predict the optimum therapeutic level after administration. A cross-sectional study to determine the pharmacokinetic parameters and safety of intravenous valproate for future application was conducted in Thai children from January to December 2008. There were eleven children, age-range 1-15 years (mean age 9.5 years) enrolled. Valproate of 15-20 mg/kg was administrated intravenously at the rate of 3 mg/kg/min, followed by 6 mg/kg every 6 h. Valproate level was determined prior to the initial dose and at ½, 1, 2, 4, 5, and 6 h postdose. Complete blood count, serum ammonia, and liver function tests were collected prior to the initial dose and at 6 h. Median loading dose was 19 mg/kg (range 15-20.5 mg/kg). Median maximum concentration at 30 min after infusion was 98.8 mcg/mL (range 67-161 mcg/mL). Median volume of distribution was 0.20 L/kg (range 0.15-0.53 L/kg). Median half-life was 9.5 h (range 4.4-24.2 h). Median clearance was 0.02 L/h/kg (range 0.01-0.05 L/h/kg). Six hours after initial dose, eight children did not have recurrent seizure. One child had brief seizure at 20 min after initial dose. Seizure recurred in two children at 4th and 5th hour. Asymptomatic transient elevation of serum ammonia was observed in two children. Volume of distribution of 0.20 L/kg could be applied for initial intravenous administration with a favorable efficacy.

Status epilepticus

Status epilepticus is a common neurological emergency in childhood and associated with significant morbidity and mortality. Status epilepticus (SE) has been defined as continuous seizure activity lasting more than 30 min or 2 or more seizures in this duration without gaining consciousness between them. However, the operational definition has brought the time down to 5 min. Management can be broadly divided into initial stabilization, seizure termination, and evaluation and treatment of the underlying cause. Diagnostic evaluation and seizure control should be achieved simultaneously to improve outcome. Seizure termination is achieved by pharmacotherapy. Benzodiazepines are the first line drugs for SE. Commonly used drugs include lorazepam, diazepam, and midazolam. In children without an IV access, buccal or nasal midazolam or rectal diazepam can be used. Phenytoin as a second line agent is usually indicated when seizure is not controlled after one or more doses of benzodiazepines. If the seizures continue to persist, valproate, phenobarbitone or levetiracetam is indicated. Midazolam infusion is useful in refractory status epilepticus. Thiopentone, propofol or high dose phenobarbitone are considered for treatment of refractory status epilepticus. Prolonged SE is associated with higher morbidity and mortality. Long term neurological sequelae include epilepsy, behavioural problems, cognitive decline, and focal neurologic deficits.

Medical treatment of pediatric status epilepticus

Status epilepticus (SE) is a common pediatric neurologic emergency that refers to a prolonged seizure or recurrent seizures without a return to baseline mental status between seizures. Appropriate treatment strategies are necessary to prevent prolonged SE and its associated morbidity and mortality. This review discusses the importance of a rapid and organized management approach, reviews data related to commonly utilized medications including benzodiazepines, phenytoin, phenobarbital, valproate sodium, and levetiracetam, and then provides a sample SE management algorithm.

Rapid infusion of a loading dose of intravenous levetiracetam with minimal dilution: a safety study

Intravenous antiepileptic drugs are required in patients needing urgent treatment or unable to take oral medication. The safety of intravenous levetiracetam has been established in prospective studies of adult epilepsy and healthy participants. The authors performed a prospective, single-center study to evaluate the safety of a rapid loading dose of intravenous levetiracetam. Patients were divided into 3 equal dosing groups (N = 15 each): 20, 40, and 60 mg/kg (corresponding to maximum doses of 1, 2, and 3 g). Electrocardiogram and safety assessment were performed during the infusion. Ages were 4 to 32 years. Postinfusion serum levetiracetam concentrations were 14 to 189 microg/mL. There were no significant changes in blood pressure, no local infusion site reactions, and no electrocardiogram abnormalities. The authors concluded that high serum levels of parenteral levetiracetam can be achieved rapidly and safely, in a small infusion volume. This finding has important implications for the treatment of status epilepticus.

Anticonvulsant medications in the pediatric emergency room and intensive care unit

Seizures are common in pediatric emergency care units, either as the main medical issue or in association with an additional neurological problem. Rapid treatment prolonged and repetitive seizures or status epilepticus is important. Multiple anti-convulsant medications are useful in this setting, and each has various indications and potential adverse effects that must be considered in regard to individual patients. This review discusses new data regarding anticonvulsants that are useful in these settings, including fosphenytoin, valproic acid, levetiracetam, and topiramate. A status epilepticus treatment algorithm is suggested, incorporating changes from traditional algorithms based on these new data. Treatment issues specific to complex medical patients, including patients with brain tumors, renal dysfunction, hepatic dysfunction, transplant, congenital heart disease, and anticoagulation, are also discussed.